Exterior Door Selection and Installation

New exterior doors often fit and insulate better than older types. If you have older doors in your home, replacing them might be a good investment, resulting in lower heating and cooling costs. If you're building a new home, you should consider buying the most energy-efficient doors possible.

When selecting doors for energy efficiency, it's important to first consider their energy performance ratings in relation to your climate and home's design. This will help narrow your selection.

Types of Doors

One common type of exterior door has a steel skin with a polyurethane foam insulation core. It usually includes a magnetic strip (similar to a refrigerator door magnetic seal) as weatherstripping. If installed correctly and if the door is not bent, this type of door needs no further weatherstripping.

The R-values of most steel and fiberglass-clad entry doors range from R-5 to R-6 (not including the effects of a window.) For example: A 1-1/2 inch (3.81 cm) thick door without a window offers more than five times the insulating value of a solid wood door of the same size.

Glass or "patio" doors, especially sliding glass doors, lose heat much faster than other types of doors because glass is a very poor insulator. Most modern glass doors with metal frames have a thermal break, which is a plastic insulator between inner and outer parts of the frame. Models with several layers of glass, low-emissivity coatings, and/or low-conductivity gases between the glass panes are a good investment, especially in extreme climates. Over the long run, the additional cost is paid back many times over in energy savings. When buying or replacing patio doors, keep in mind that swinging doors offer a much tighter seal than sliding types.

Also, with a sliding glass door, it's impossible to stop all the air leakage around the weatherstripping and still be able to use the door. Also, after years of use, the weatherstripping wears down so air leakage increases as the door ages. If the manufacturer has made it possible to do so, you can replace worn weatherstripping on sliding glass doors.

Installation

When you buy a door, it will probably be a pre-hung frame. Pre-hung doors usually come with wood or steel frames. You will need to remove an existing door frame from the rough opening before you install a pre-hung door. The door frame must be as square as possible, so that the door seals tightly to the jamb and swings properly.

Before adding the interior trim, apply an expanding foam caulking to seal the new door frame to the rough opening and threshold. This will help prevent air from getting around the door seals and into the house. Apply carefully, especially with a wood frame, to avoid having the foam force the frame out of square.

If needed, you'll also want to add weatherstripping. Check the weatherstripping on your exterior doors annually to see if it needs replacement.
Storm Doors

Adding a storm door can be a good investment if your existing door is old but still in good condition. However, adding a storm door to a newer, insulated door is not generally worth the expense since you won't save much more energy.

Storm door frames are usually made of aluminum, steel, fiberglass, or wood (painted or not). Wooden storm doors require more maintenance than the other types. Metal-framed storm doors might have foam insulation within their frames.

High-quality storm doors use low-emissivity (Low-E) glass or glazing. Some doors have self-storing pockets for the glass in summer, and an insect screen for the winter. Some have fixed, full length screens and glass panels that slide out of the way for ventilation. Others are half screen and half glass, which slide past each other. Some are removable for cleaning, others are not. All of these features add some convenience and higher costs.

Never add a glass storm door if the exterior door gets more than a few hours of direct sun each day. The glass will trap too much heat against the entry door and possibly damage it.

Storm doors for patio doors are hard to find but they are available. Adding one to a new, multi-glazed, Low-E door is seldom economic. Insulated drapes, when closed for the night in the winter (or on sunny days in the summer) are also a good idea.
Weatherstripping

You can use weatherstripping in your home to seal air leaks around movable joints, such as windows or doors. To determine how much weatherstripping you will need, add the perimeters of all windows and doors to be weatherstripped, then add 5%–10% to accommodate any waste. Also consider that weatherstripping comes in varying depths and widths. Before applying weatherstripping in an existing home, you need to do the following (if you haven't already):
Detect air leaks
Assess your ventilation needs for indoor air quality.
Selection

You need to choose a type of weatherstripping that will withstand the friction, weather, temperature changes, and wear and tear associated with its location. For example, when applied to a door bottom or threshold, weatherstripping could drag on carpet or erode as a result of foot traffic. Weatherstripping in a window sash must accommodate the sliding of panes—up and down, sideways, or out. The weatherstripping you choose should seal well when the door or window is closed while allowing it to open freely.

Choose a product for each specific location. Felt and open-cell foams tend to be inexpensive, susceptible to weather, visible, and inefficient at blocking airflow. However, the ease of applying these materials may make them valuable in low-traffic areas. Vinyl, which is slightly more expensive, holds up well and resists moisture. Metals (bronze, copper, stainless steel, and aluminum) last for years and are affordable. Metal weatherstripping can also provide a nice touch to older homes where vinyl might seem out of place.

You can use more than one type of weatherstripping to seal an irregularly shaped space. Also take durability into account when comparing costs.

Application

Weatherstripping supplies and techniques range from simple to the technical. Consult the instructions on the weatherstripping package. Here are a few basic guidelines:
Measure the area to be weatherstripped twice before you cut anything.
Apply weatherstripping snugly against both surfaces. The material should compress when the window or door is shut.
When weatherstripping doors:
Choose the appropriate door sweeps and thresholds for the bottom of the doors.
Weatherstrip the entire door jamb.
Apply one continuous strip along each side.
Make sure the weatherstripping meets tightly at the corners.
Use a thickness that causes the weatherstripping to tightly press between the door and the door jamb when the door closes, without making it difficult to shut.
For air sealing windows, apply weatherstripping between the sash and the frame. The weatherstripping shouldn't interfere with the operation of the window.


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